1. Field of the Invention
This invention relates broadly to ophthalmological instruments. More particularly, this invention relates to instruments used to insert collagen rods into the punctal opening.
2. State of the Art
A variety of eye problems are related to an insufficient volume of tears on the surface of the eyes. The most common is keratoconjunctivitis sicca, also known as dry eyes. Contact lens problems are also often provoked by a lack of tear volume. A common cause for the insufficient tear volume is the drainage of tear fluid through the punctal opening of the nasal lacrimal duct and into the nasal passage, thereby removing the fluid from where it is needed at the eye surface. Furthermore, drainage of tear fluid through the nasal lacrimal duct into the nasal passage is believed to be the cause or associated with several additional problems such as post nasal drip, sinusitis, allergies, headaches, and snoring.
A number of methods for closing the punctal opening have been used to prevent drainage of tears through the nasal lacrimal duct, including suturing, laser sealing, and plugging. However, before any of the above methods are used on a patient, small collagen rods are often implanted into the punctal openings in the eyes of the patient to occlude the nasal lacrimal ducts. The physician treating the patient can then better diagnose the patient. The collagen rod implants slowly dissolve in about a week, giving the physician ample time to verify the potential clinical benefits of more permanent occlusion for a particular patient, and also to evaluate receptivity of the patient to duct occlusion.
The collagen rods intended for occluding the nasal lacrimal ducts are extremely small (approximately 2 mm in length and having a diameter of approximately 0.2 mm). Because of the small size of the collagen rods, a tool is required to insert the rods into the punctal opening. Referring now to prior art FIG. 1, the tool of the prior art used to insert collagen rods is typically a straight collagen forceps 10, the shape and size of a conventional tweezers. The collagen forceps has two arms 12, 14 resiliently hinged at a proximal portion 16 and terminating distally in two elongate tips 18, 20. Each tip has an inner flat surface 22, 24 which grips the collagen rod. The arms 12, 14, which are held by the physician, are relatively narrow and do not provide comfortable and stable finger and thumb grips. Comfortable and stable finger and thumb grips are desirable when working with very small implants close to the eye, as fine manipulation of the elongate tips is required to implant the rods into the punctal openings of the eyes. Additionally, the inner gripping surfaces 22, 24 are inadequate for gripping cylindrical collagen rods as the rods tend to slip against and rotate on the flat surface. Furthermore, prior art forceps instruments are unable to provide pre-insertion dilation of the punctal opening, nor do they have the ability to push the collagen rod into the punctal opening such that the collagen rod is pushed below the punctal opening. A second instrument is required for those purposes.